694 TECHNICAL CHEMISTRY 



For manufacturing purposes both might as well not exist. The 

 only human beings that can live under the conditions obtaining in 

 these tropical jungles are the natives; but the distance to which the 

 natives can transport the rubber is comparatively limited. Although 

 rubber-bearing trees are now being cultivated in the more easily 

 inhabitable portion of the tropics, it will be a long time before this 

 source of supply is an important factor in the market. And thus it 

 comes that the synthesis of India rubber presents to-day from at 

 least the technical side, one of the most promising problems in 

 chemistry. 



The investigation of India rubber is greatly handicapped by the 

 fact that it exists only in the colloidal state. The difficulties are 

 perhaps more largely physical than chemical; that is, it is the mole- 

 cular aggregation rather than the atomic structure of the individual 

 molecule which presents such almost insurmountable difficulties. 

 There are no clearly defined melting-points, boiling-points, tenden- 

 cies to crystallize or any of those means of separating mixtures or 

 characterizing individuals which aid in the investigation of most 

 organic compounds. The researches of Weber and Harries, resulting 

 in the establishment of the much-needed methods of analyses, have 

 been of incalculable advantage to all those working with either the 

 raw or the manufactured article. In many directions also, the paths 

 along which important results are to be obtained have already been 

 blazed by these investigators. Probably no other field presents such 

 difficulties of manipulation, in addition to such profound problems 

 of organic chemistry, as does the investigation of India rubber; but 

 on the other hand, few such unlimited opportunities for valuable work 

 are offered in the field of chemical research. 



Under the general head of utilization of trade-wastes may be con- 

 sidered a large number of technical problems, the solution of which 

 would not only add wonderfully to the economic resources of the 

 country, but would aid in the solution of that much vexed question, 

 river-pollution. We have already mentioned the soda and sulphite 

 liquor resulting from the manufacture of cellulose fiber from wood. 

 Of almost equal importance is the waste yeast which is daily pro- 

 duced in the brewing of beer and ale. An extract of this yeast has 

 a food value, as shown by analysis, equal to the best meat extracts. 

 As the quantity of yeast allowed to go to waste is from one to two 

 pounds for every barrel of beer brewed, we can form estimates of the 

 great amount of this material at hand. Arsenic sulphide from 

 the purification of crude acids, grease from the washing of wool, the 

 utilization of city garbage and many other problems of this order are 

 everywhere in evidence. It is not within the compass of this discus- 

 sion to mention these almost innumerable sources of manufacturing 

 waste which exist in the chemical industry; but keen competition 



